My question is about the filters water flow. Is it (don't laugh at me) coming from the bottom up? I know some water is being pulled up to the wheels. But I can not tell where the water enters the main media compartment. It's dark in there. It "looks" as though water pours from the top down and that makes no sense to me. I have no intention of using the Marineland refills. Just foam and media bags of pumice stone. Want to know how I should orient them. Thanks in advance!!